PG and Beads

[preembargo]

The question has been asked, whether or not one should apply propylene glycol solution to silica gel beads. The concern is that the PG would clog the nanopores of the beads.

According to Steve Saka in “The Ultimate Cigar Manifesto”, the humi crystals or humi gel available in jars and tubes is a compound comprised of silica gel bounded with a salt derivative to maintain the relative humidity of 70% RH. JR Cigars version of “The Ultimate Cigar Manifesto”, adds that the silica beads in these gels are impregnated with PG solution. This would seem to answer the question, right? But does this really apply to Climaxx type beads, or KLH? I trust Mr. Saka but are we going to take the word of Lew Rothman as he embellishes on the work of Mr. Saka in order to sell a mediocre product? Where’s the science?

In order to come to a definitive answer….I cheated. I’ve sent the following email to DOW Chemicals.

________________________________________

To whom it may concern,

I understand that PG is highly soluble and biodegradable; this with its hygroscopic nature makes it ideal for use in regulating and maintaining a specific relative humidity within a closed environment. My question concerns its effect on a nanoporous media such as regular density silica gel beads. I would appreciate very much if you would provide or direct me to documentation which might show whether propylene glycol will or will not clog the pores of the media if applied directly to the beads or indirectly by way of a wicking device, i.e. a sponge or other absorbent material.

Thank you for your assistance,
Michael Beach
________________________________________

While waiting for their response I will continue to search the internet for information. After I sent the email, I did find some of DOW’s literature on PG. It may take some time to decipher (I’m not really a scientist, I just play one on CP) but I’ll do my best. I’d be more than happy to forward it on to anyone who enjoys reading technical literature and would like to help the community come to a definitive conclusion.

Stay tuned.....

 

[N2Advnture]

...the humi crystals or humi gel available in jars and tubes is a compound comprised of silica gel bounded with a salt derivative to maintain the relative humidity of 70% RH. JR Cigars version of “The Ultimate Cigar Manifesto”, adds that the silica beads in these gels are impregnated with PG solution. This would seem to answer the question, right?

The "humi crystals" & "humi gels" are not the same at humidification beads like the RH Beads, Heartfelt Beads or Climmax Beads. Completely different products and PG should NOT be used on them. :thumbs:

Hope this helps
~Mark

 

[Allofus123]

........the humi crystals or humi gel available in jars and tubes is a compound comprised of silica gel bounded with a salt derivative to maintain the relative humidity of 70% RH. JR Cigars version of “The Ultimate Cigar Manifesto”, adds that the silica beads in these gels are impregnated with PG solution. This would seem to answer the question, right? But does this really apply to Climaxx type beads, or KLH?

Apples and Oranges IMO. The humi crystals/humi gel are not beads.

Will be interesting to see what Dow says. Wonder if they actually have test data using PG and silica gel beads. PM coming to you with my e-mail addie for the info you have. Thanks and good work.

Another question I had when this came up was why? Why use the PG? Seems counter productive since the beads will regulate rh without the PG. To me, if you're going to use PG you just as well use florist foam and be done with it. I just don't see the advantage to adding it to beads. Am I missing something?

 

[viper139]

...the humi crystals or humi gel available in jars and tubes is a compound comprised of silica gel bounded with a salt derivative to maintain the relative humidity of 70% RH. JR Cigars version of “The Ultimate Cigar Manifesto”, adds that the silica beads in these gels are impregnated with PG solution. This would seem to answer the question, right?

The "humi crystals" & "humi gels" are not the same at humidification beads like the RH Beads, Heartfelt Beads or Climmax Beads. Completely different products and PG should NOT be used on them. :thumbs:

Hope this helps
~Mark

Mark is 10,000% correct, any product that is a "humi gel" or expanding gel are not the same. Adding PG to RH Beads, Heartfelt Beads or Climmax Beads will ruin them. DO NOT use PG on our products.

David

 

[LilBastage]

The silica gel beads are 90% silica gel (SiO2) and lithium chloride (LiCl) [some variation in ratio may appear between brands and specific uses]. The humi-gel stuff are anionic polyacrylamide polymers.

These are not the same thing. The humi-gel absorbs what you give it and gives off what it absorbs. It's basically a bunch of small super capacity sponges. There is no humidity regulation inherent to the product. That's why they are impregnated with PG solution.

The beads that everyone talks about and that various places sell have the humidity regulation capacity "built-in". IT is their composition that provides the control. KLH acts in the same regard. The difference being in the conditioning. You can buy beads that work from 40%-80% humidity levels if you look for them as a museum use product. PG is not only unnecessary, it may in fact clog the beads.

Hope that helps.

 

[preembargo]

No question that gel and beads are different products. I only mention them because in describing the gels Lew says on his website:

"These are beads of silica gel bound with a salt derivative designed to retain and expel large quantities of water. When treated with Propylene Glycol these dioxide beads work to maintain the same basic relative humidity hysteresis loop of 70% RH."

which would appear to endorse the use of PG solution on beads.

IMO, anything Lew say's needs to be looked at closer or dismissed altogether.

So, I would like to investigate whether one could (or should) use PG as a rapid conditioner. And I would consider applying indirectly using a wicking device rather than spraying directly onto the beads. Once the beads are set at 70% there would be no need to use the solution again unless reconditioning becomes necessary. It should also be pointed out that should the science determine that there are no pitfalls to using PG, I am only investigating using the solution on 70% beads, using it on 60% or 65% beads will recondition them to 70%.

Kenny, thank you for the offer, I'll get that to you this afternoon. Mark and David, would you be able to send any technical data that you have as well? Thank you gentlemen, I look forward to the discussions.

 

[LilBastage]

Does the PG in floral foam act as a buffer by slowing the rate of evaporation of the water, essentially "blocking" the release of water molecules?

If that is the case, would it not stand to reason that in silica gel beads the PG would act the same way? In effect wouldn't it block the release of water molecules in both adsorption and desorption phases of the process?

PG evaporates about 20 times slower than water. Would the addition of PG to the beads effectively slow down their response to render them practically useless for the given application?

Is the size of the PG molecule a factor in it's effect on the beads?

These are just some questions, I really don't know the answers. Just thinking out loud here.

An interesting fact I found: the internal surface area of a teaspoon full of silica gel is equivalent to a football field. That's a lot of surface area!

I'm looking forward to your findings.

(Just as an addition, I think Rothman is talking out of his arse more than 75% of the time. He's a successful salesman, that's for sure.)

 

[preembargo]

Good questions LilBastage

Is the size of the PG molecule a factor in it's effect on the beads?

This is a model of the PG molecule

OH OH​

CH3 CH - CH2

Typical silica gel material has a bulk density of 400-600 g/l, pore volume of approximately 50-250 angstroms.

Does this address that question? ???



First response from DOW

Michael,

Thank you for contacting The Dow Customer Information Group. We have received your technical request and escalated it onto the business who will be responding via email within the next 2-5 business days.

Dow Customer Information Group
1-800-447-4369
8AM - 5PM EST M-F
www.dow.com

 

[preembargo]

I just got a voice mail from Dennis at DOW. He said he would like to better understand the application in which I want to use the PG but the PG should not clog the beads, that the glycol will enhance the hygroscopic nature of the beads. I’ll give him a call back this afternoon to discuss this in detail.

 

[Mrepp]

Our company has done work with dow, good company. Any how you have to remember that there's a difference between beads and silica gel, PG is what most call "heavy water" which is why is feels oily to the touch. What David and Mark are saying is because its heavy water it will clog the pores of the beads. I'm guessing that the shell or hard out side of beads is actually tyvek. The actual way vip's beads maintain is unknown to me. As far as the other silica crystals are concerned I believe PG will work with it.

 

[Ginseng]

Watching intently. I'm curious to hear Dow's response. I'll reserve my comments until we see how that plays out.

Wilkey

 

[LilBastage]

Good questions LilBastage

Is the size of the PG molecule a factor in it's effect on the beads?

This is a model of the PG molecule

OH OH​

CH3 CH - CH2

Typical silica gel material has a bulk density of 400-600 g/l, pore volume of approximately 50-250 angstroms.

Does this address that question? ???

I have no idea?! :laugh: My wife is the scientist around here. I know just enough to make myself VERY dangerous at times. :laugh:

Seriously, an angstrom is 1/10,000,000,000m if google is to be trusted. (yeah, I had to look it up ) and a Hydrogen atom is 1 angstrom across. According to what I have found, liquid water is approximately 2.75 angstroms across. I can't find any data on PG in that regard.

I do wonder, however, if the non-aqueous nature of PG would block the silica from adsorbing the water altogether? It seems that any presence of PG within the pores of the silica would prevent water from entering those same pores.

This is all interesting, but I'm getting a headache...:laugh:

 

[preembargo]

I returned Dennis' call (Dennis is QC for DOW's propylene glycol business) and had to leave a message. I listened again to Dennis' voice mail before I called. I'm glad I did, he said "Propylene Glycol is highly hygroscopic and will pull moisture from the air. I have no reason to think that the glycol would plug the silica gel, in fact the silica gel would enhance the hygroscopic abilities of the glycol" He said 'gel' but may not have understood that I am asking about silica gel beads so this could still go either way. In my message I made sure to be specific and explained that I would be using amorphous silica Gel beads like that used for kitty litter and the PG would be used in a 50/50 solution of PG and distilled water. I asked him if the solution would clog the pores in the beads.

I then of course told him that I'm impressed with his quick response.

 

[Allofus123]

I know just enough to make myself VERY dangerous at times. :laugh:

LOL... that applies to most of us here. :laugh: :sign:

Any chance we can find a manufacturer of Silica gel beads to comment on this along with the Dow comments? Someone other than a salesman. Really need someone with the technical understanding of Silica gel beads and its working properties.

BTW, this wkend I'm going to set up an experiment mixing pre conditioned beads and un conditioned beads and see if I can bring the unconditioned beads up to the rh in the conditioned beads without using anything but an occasional misting of the conditioned beads. I'll start another thread when I get it set up and post pictures along with a daily update.

 

[preembargo]

Any chance we can find a manufacturer of Silica gel beads to comment on this along with the Dow comments? Someone other than a salesman. Really need someone with the technical understanding of Silica gel beads and its working properties.

Good call Kenny,

I’ve emailed Sphinx Adsorbents, Inc. in Springfield, MA

________________________________________
From: Michael Beach [mailto:*****@charter.net]
Sent: Wednesday, March 21, 2007 10:39 PM
To: '*****@muthassociates.com'
Subject: Silica gel beads and propylene glycol

To whom it may concern,

I understand that silica gel beads have a hygroscopic nature which makes them an ideal buffering agent for use in regulating and maintaining a given relative humidity within a closed environment. Though silica beads are typically used as a desiccant, they are commonly used to preserve fine art and archival records due to there excellent adsorption and desorption properties once properly conditioned to a desired RH level.

I am attempting to determine a suitable conditioning agent to condition silica gel beads to 70%. I’m aware of the hygroscopic properties of propylene glycol and feel it might be used as ‘rapid’ conditioner to set the silica beads to the desired 70%. My concern is the effect of ‘PG’ on a nanoporous media, specifically will a 50/50 solution of propylene glycol and distilled water adversely affect the ability of silica gel beads to adsorb/desorb. I would appreciate very much if you would provide or direct me to documentation which might show whether propylene glycol will or will not clog the pores of the silica beads thereby hindering the capillarity of the beads.

Thank you for your assistance,
Michael Beach
________________________________________

 

[Brickhouse]

Jeez Mike, why don't you at least put some effort into this.

 

[LilBastage]

I'm looking forward to the results of this. The headache just went away from all the stuff I was wading through earlier! :laugh:

I put in an e-mail to the Art-Sorb folks. I'll report the response, if any.

 

[preembargo]

Wow, this is moving much faster than I anticipated.

I just spoke with Dennis at DOW, and he said "PG is 100% immiscible and soluble in any proportion of water and will not obstruct the beads' pores, there's no reason not to use it with silica beads". He also echoed that outside of conditioning the beads there's no reason TO use it with silica beads.

There are still inquiries out to a bead manufacturer and a distributor as well as one I sent out this morning to Art Preservation Services, NY. I'm very interested in what their response will be.


edit to add: Wilkey, what does ‘immiscible’ mean?

 

[Ginseng]

Immiscible means "does not mix with." As in water and oil.

The quote you posted does not seem to make sense, but still...

When mixing PG with water, which I have done many times over the years for my coolers, what you see is that initially, the mixture looks like oil in water. It takes a few minutes of vigorous stirring to make the solution appear clear. I recall reading somewhere that PG does not actually form a true solution with water but I can't seem to find that reference.

I do not think that using PG/water with beads is a constructive route to take. Primarily, the reason is that the mechanism whereby PG/W works to maintain a target humidity is different from that of hydrated silica gel and that of saturated salt solutions. IMO, each system is best used in isolation so that you do not have competing systems in your humi.

Wilkey

 

[NullSmurf]

Wow, this is moving much faster than I anticipated.

I just spoke with Dennis at DOW, and he said "PG is 100% immiscible and soluble in any proportion of water and will not obstruct the beads' pores, there's no reason not to use it with silica beads". He also echoed that outside of conditioning the beads there's no reason TO use it with silica beads.

There are still inquiries out to a bead manufacturer and a distributor as well as one I sent out this morning to Art Preservation Services, NY. I'm very interested in what their response will be.


edit to add: Wilkey, what does 'immiscible' mean?

It describes something not water solubile, like oil and water. I think it's typo. That should be miscible. PG and water are 100% miscible. PG in the beads would act as a regulator, conditioning the beads from the start. PG is organic and it will break down, so the conditioning would be limited. I think it would be better NOT to use PG.